Food groups and colon cancer risk in African-Americans and Caucasians

The disparities in colon cancer incidence between African-Americans and other U.S. ethnic groups are largely unexplained. This report examines associations of various food groups with colon cancer in African-Americans and Caucasians from a case-control study. Incident cases of histologically confirmed colon cancer, age 40-80 years, (n = 613) and matched controls (n = 996) were interviewed in-person to ascertain potential colon cancer risk factors. Diet over the year before diagnosis or interview date was assessed using a validated food frequency questionnaire adapted to include regional foods. Multivariate logistic regression models estimated energy-adjusted and non-energy adjusted odds ratios (OR). Controls generally reported higher consumption (daily amount and weekly frequency) of fruits, vegetables and dark green, deep yellow fruits/vegetables, whereas cases consumed more refined carbohydrates and fats, oils and snacks. Regardless of ethnic group or energy adjustment, high and frequent vegetable consumption (particularly dark green vegetables) was protective, consistent with 20-50% reductions in risk. In Caucasians, high refined carbohydrate and red meat consumption (amount and frequency) was associated with a statistically significant 2-fold increased risk in non-energy adjusted models. In African-Americans, frequent intake of dairy foods was associated with a doubling in risk (OR = 1.9, 95% CI = 1.1-3.4) in non-energy-adjusted models, whereas frequent fruit consumption correlated with a nonsignificant 30% lower risk. These findings add to growing evidence that plant foods may protect against colon cancer; however, the effects of the other food groups varied by ethnic group and energy adjustment. These results may also explain some of the ethnic differences in colon cancer incidence. (C) 2004 Wiley-Liss, Inc.